The present invention relates to a rubber composition for coating a textile cord and a tire using the rubber composition.
Generally, a heavy load is applied to automobile tires, and thus, as a reinforcing material, a steel cord has been used for a breaker, and a textile cord has been used for a carcass. Since a tire generates heat particularly during running, if the rubber and a cord are peeled apart, crucial damage is caused to the tire. When a steel cord is used as a cord of a carcass, there is a problem that steering stability, ride quality, rolling resistance etc. are deteriorated.
Conventionally, raw materials derived from petroleum resources such as carbon black have been mainly used in the rubber composition for coating a textile cord. However, in recent years, interests in environmental preservation on the earth have grown and automobiles not being excepted, regulations for suppressing CO2 emissions are being enforced. Further, since petroleum resources are limited and the supply thereof has been decreasing year by year, oil prices are expected to increase in the future, and consequently, there will be a limited on the uses of materials derived from petroleum resources such as carbon black. In addition, as for tire performance, it is necessary that rolling resistance is lowered in order to improve fuel efficiency to lower the cost on the environment, and that durability (rubber strength) is improved to run for the long period of time.
As a means for lowering rolling resistance, it is known to use silica which is a raw material derived from resources other than petroleum resources instead of carbon black. When silica is compounded instead of carbon black, not only is rolling resistance reduced, but also the ratio of the raw material derived from petroleum resources can be decreased, the effect on the environment can be taken into consideration, and a decrease in the use of the petroleum supply in the future can be achieved there is a problem in that Mooney viscosity is increased, and processability is deteriorated.
In addition, as another means for lowering rolling resistance, it is known to reduce the amount of carbon black that is used. When the amount of carbon black is reduced, not only is rolling resistance lowered, but also the ratio of the raw material derived from petroleum resources can be decreased, the effect on the environment can be taken into consideration, and a decrease in the use of the petroleum supply in the future can be achieved. But there is a problem in that rubber strength is lowered.
JP-A-2003-63206 discloses an ecological tire excellent in rolling resistance property, processability, and ride quality, in which the ratio of specific resources other than petroleum oil in the tire is increased by using carcass ply topping produced using a specific resource other than petroleum oil. However, this ecological tire does not improve both rolling resistance property and processability, and the rubber hardness thereof is not excellent as compared with a tire constituted of raw materials derived from petroleum resources as a main component. Thus, the necessity of improvement in properties still remains.